U.S. patent number 7,797,992 [Application Number 12/113,694] was granted by the patent office on 2010-09-21 for control apparatus for a source of rotational drive force.
This patent grant is currently assigned to Toyota Jidosha Kabushiki Kaisha. Invention is credited to Masato Kaigawa, Seiji Kuwahara.
United States Patent |
7,797,992 |
Kuwahara , et al. |
September 21, 2010 |
Control apparatus for a source of rotational drive force
Abstract
A control apparatus for controlling a source of rotational drive
force based on a target rotational speed. The control apparatus
includes a target model rotational speed calculation section, an
actual rotational speed detection section, and a target rotational
speed adjustment section. The target model rotational speed
calculation section calculates a rotational speed corresponding to
a target drive force of the source as a target model rotational
speed. The actual rotational speed detection section detects an
actual of the source. The target rotational speed adjustment
section sets the target rotational speed by correcting a value of
the target model rotational speed calculated by the target model
rotational speed calculation section to gradually approach the
actual rotational speed detected by the actual rotational speed
detection section. Accordingly, hunting of the engine during
control is prevented and the deviation between the actual
rotational speed and the target rotational speed is reduced or
prevented.
Inventors: |
Kuwahara; Seiji (Toyota,
JP), Kaigawa; Masato (Toyota, JP) |
Assignee: |
Toyota Jidosha Kabushiki Kaisha
(Toyota-shi, JP)
|
Family
ID: |
39970282 |
Appl.
No.: |
12/113,694 |
Filed: |
May 1, 2008 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20080281502 A1 |
Nov 13, 2008 |
|
Foreign Application Priority Data
|
|
|
|
|
May 11, 2007 [JP] |
|
|
2007-126452 |
|
Current U.S.
Class: |
73/114.25 |
Current CPC
Class: |
F02D
31/002 (20130101); B60W 20/00 (20130101); B60W
10/04 (20130101); F02D 41/1401 (20130101); B60W
2710/0644 (20130101); F02D 41/0225 (20130101); B60W
2710/1038 (20130101); F02D 2400/12 (20130101); B60W
2510/0638 (20130101); F02D 2250/18 (20130101); B60W
2520/28 (20130101) |
Current International
Class: |
G01M
15/04 (20060101) |
Field of
Search: |
;73/114.04,114.24,114.25 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
43 27 912 |
|
Sep 1994 |
|
DE |
|
198 06 393 |
|
Aug 1999 |
|
DE |
|
2003-120349 |
|
Apr 2003 |
|
JP |
|
2003-170759 |
|
Jun 2003 |
|
JP |
|
Primary Examiner: McCall; Eric S
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier
& Neustadt, L.L.P.
Claims
What is claimed is:
1. A control apparatus for controlling a source of a rotational
drive force based on a target rotational speed, the control
apparatus comprising: a target model rotational speed calculation
section for calculating a rotational speed corresponding to a
target drive force of the source as a target model rotational
speed; an actual rotational speed detection section for detecting
an actual rotational speed of the source; and a target rotational
speed adjustment section for setting the target rotational speed by
correcting a value of the target model rotational speed calculated
by the target model rotational speed calculation section to
gradually approach the actual rotational speed detected by the
actual rotational speed detection section.
2. A control apparatus of claim 1, wherein the source is a
rotational drive force source for a vehicle.
3. A control apparatus of claim 1, wherein the source of rotational
drive force is an internal combustion engine, an electric motor, or
a hybrid engine using both the internal combustion engine and the
electric motor.
4. A control apparatus of claim 1, wherein the target drive force
of the source is a target engine torque.
5. A control apparatus of claim 1, wherein the target rotational
speed adjustment section performs the correction based on a
correction amount, wherein the correction amount is determined in
accordance with a PI control calculation or an I control
calculation while setting a difference between the target model
rotational speed (NEm) and the actual rotational speed as a limit
value.
6. A control apparatus of claim 1, wherein the target rotational
speed adjustment section performs the correction based on a first
order lag process of a difference between the target model
rotational speed and the actual rotational speed.
7. A control apparatus of claim 1, wherein the target rotational
speed adjustment section, wherein the correction amount gradually
increases while setting a difference between the target model
rotational speed (NEm) and the actual rotational speed as a limit
value.
8. A control apparatus of claim 1, wherein the source includes an
internal combustion engine and the control amount for controlling
the source is a throttle opening degree or a fuel injection
amount.
9. A control apparatus of claim 1, wherein the target rotational
speed adjustment section cancels the correction and initializes a
value of the target rotational speed to a value of the target model
rotational speed, when the target model rotational speed is rapidly
changed.
10. A control apparatus of claim 9, wherein the time when the
target model rotational speed is rapidly changed is when an
absolute value of a change amount of the target model rotational
speed per unit time becomes larger than a reference value.
11. A control apparatus of claim 9, wherein the time when the
target model rotational speed is rapidly changed is when the target
model rotational speed separates from or intersects the actual
rotational speed.
12. A control apparatus for controlling a source of a rotational
drive force, the control apparatus comprising: a target rotational
speed calculation section for calculating a target rotational speed
of the source of the rotational drive force; a target drive force
setting section for setting a target drive force generated by the
source; and a control amount calculation section for calculating a
control amount of the source based on the target rotational speed
calculated by the target rotational speed calculation section and
the target drive force set by the target drive force setting
section, by using a predetermined rotational drive force model for
the source, wherein the target rotational speed calculation section
includes: a target model rotational speed calculation section for
calculating a rotational speed corresponding to the target drive
force as a target model rotational speed based on the target drive
force set by the target drive force setting section, by using a
predetermined rotational drive force source output transmission
model of the source; an actual rotational speed detection section
for detecting an actual rotational speed of the source; and a
target rotational speed adjustment section for setting the target
rotational speed by correcting a value of the target model
rotational speed calculated by the target model rotational speed
calculation section to gradually approach the actual rotational
speed detected by the actual rotational speed detection
section.
13. A control apparatus of claim 12, wherein a rotational drive
force of the source is transmitted by an output transmission
system, wherein the output transmission system include a torque
converter, wherein the output transmission model reflects a state
of the torque converter.
14. A control apparatus of claim 13, further comprising an output
side rotational speed detection section for detecting an output
side rotational speed on an output side of the torque converter,
wherein the target model rotational speed calculation section
calculates the target model rotational speed based on the output
side rotational speed detected by the output side rotational speed
detection section and the target drive force set by the target
drive force setting section, by using a torque converter model as
the output transmission model.
15. A control apparatus of claim 14, wherein a rotational drive
force of the source is transmitted by the output transmission
system, wherein the output transmission system includes a
transmission arranged on an output side of the torque converter and
an output shaft rotational speed detection section for detecting an
output shaft rotational speed of the transmission, wherein the
output side rotational speed detection section calculates the
output side rotational speed based on the output shaft rotational
speed detected by the output shaft rotational speed detection
section and a gear ratio of the transmission.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
The entire disclosure of Japanese Patent Application No.
2007-126452, filed on May 11, 2007, is expressly incorporated by
reference herein.
FIELD OF THE INVENTION
The present invention relates to a control apparatus for
controlling the source of a rotational drive force based on target
rotational speed.
BACKGROUND
In the field of internal combustion engines for vehicles, for
example, there has been proposed an apparatus for controlling an
internal combustion engine in such a manner as to achieve a torque
output and a vehicle acceleration corresponding to an accelerator
operation of the driver as described in Japanese Unexamined Patent
Publication Nos. 2003-120349 and 2003-170759.
In the patent documents cited above, in order to calculate a
control amount for achieving a target drive force such as a target
torque, actual engine speed is used as one of parameters. However,
even if actual torque approaches or coincides with target torque in
accordance with this control, a comparatively long dead time is
required until the engine speed actually reaches a level
corresponding to the target torque. Accordingly, if a control
amount is calculated based on the actual engine speed, hunting of
the engine may be generated during the driving of the internal
combustion engine.
In order to prevent the hunting from occurring, it is possible to
determine target rotational speed corresponding to a target drive
force of an internal combustion engine drive system by using a
model as a preset internal combustion engine model or an output
transmission model and determine a control amount based on the
target rotational speed. However, such a model represents a
standard or average relation and does not necessarily match an
actual individual internal combustion engine or output transmission
system with high precision. Accordingly, deviation may occur
between the engine speed actually reached and the target rotational
speed at steady state, which can reduce the precision of various
controls.
SUMMARY OF THE INVENTION
An object of the present invention is to prevent hunting during
control in a control apparatus for a source of a rotational drive
force, and to reduce or prevent deviation between actual rotational
speed and target rotational speed.
In one aspect, a control apparatus for controlling a source of a
rotational drive force based on a target rotational speed is
provided. The control apparatus comprises a target model rotational
speed calculation section, an actual rotational speed detection
section, and a target rotational speed adjustment section. The
target model rotational speed calculation section operates to
calculate a rotational speed corresponding to a target drive force
of the source as a target model rotational speed. The actual
rotational speed detection section operates to detects an actual
rotational speed of the source. The target rotational speed
adjustment section operates to set the target rotational speed by
correcting a value of the target model rotational speed calculated
by the target model rotational speed calculation section to
gradually approach the actual rotational speed detected by the
actual rotational speed detection section.
In the second aspect, a control apparatus for controlling a source
of a rotational drive force is provided. The control apparatus
comprises a target rotational speed calculation section, a target
drive force setting section, and a control amount calculation
section. The target rotational speed calculation section operates
to calculates a target rotational speed of the source of the
rotational drive force. The target drive force setting section
operates to set a target drive force generated by the source. The
control amount calculation section operates to calculate a control
amount of the source based on the target rotational speed
calculated by the target rotational speed calculation section and
the target drive force set by the target drive force setting
section, by using a predetermined rotational drive force model for
the source. The target rotational speed calculation section
includes a target model rotational speed calculation section, an
actual rotational speed detection section, and a target rotational
speed adjustment section. The target model rotational speed
calculation section operates to calculate a rotational speed
corresponding to the target drive force as a target model
rotational speed based on the target drive force set by the target
drive force setting section, by using a predetermined rotational
drive force source output transmission model of the source. The
actual rotational speed detection section operates to detect an
actual rotational speed of the source. The target rotational speed
adjustment section operates to set the target rotational speed by
correcting a value of the target model rotational speed calculated
by the target model rotational speed calculation section to
gradually approach the actual rotational speed detected by the
actual rotational speed detection section.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a source of rotational drive force, a
control apparatus for the source of the rotational drive force, and
an output transmission system for the rotational drive force from
the source in accordance with a first embodiment;
FIG. 2 is a control block diagram illustrating an engine output
torque controlling portion;
FIG. 3 is an explanatory view of a map MAPte for calculating a
target engine torque Te;
FIG. 4 is a control block diagram illustrating a target rotational
speed adjustment section;
FIG. 5 is an explanatory view of a map MAPtat for calculating a
target throttle opening degree TAt;
FIG. 6 is a flow chart of an engine output torque control
process;
FIG. 7 is a flow chart of a target rotational speed adjustment
process;
FIG. 8 is a timing chart showing a control example of the first
embodiment;
FIG. 9 is a control block diagram illustrating a target rotational
speed adjustment section in accordance with a second
embodiment;
FIG. 10 is a flow chart of a target rotational speed adjustment
process;
FIG. 11 is a timing chart showing a control example of the second
embodiment; and
FIG. 12 is a flow chart of a target rotational speed adjustment
process in accordance with a third embodiment.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
FIG. 1 shows a block diagram of a source of rotational drive force,
a control apparatus for the source of the rotational drive force,
and an output transmission system for rotational drive force from
the source in accordance with a first embodiment of the present
invention. In this drive system, rotational drive force output from
a gasoline engine 2, which serves as a source of rotational drive
force for a vehicle, is transmitted to drive wheels 10 and 12 via a
torque converter 4, an automatic transmission 6 and a differential
gear 8.
A throttle valve 16 is provided in an air intake path 14 of the
gasoline engine 2. A throttle opening degree TA of the throttle
valve 16 can be adjusted by a drive motor 16a. The throttle opening
degree TA is detected by a throttle opening degree sensor 16b and
is sent to an engine output torque control device 18, which serves
as the control apparatus for the source of rotational drive
force.
The engine output torque control device 18 receives a signal from
an engine speed sensor 20 and an output rotational speed sensor 22
in addition to the throttle opening degree TA. The engine speed
sensor 20 detects an actual rotational speed NE (i.e., rotational
rate) corresponding to an actual rotational speed of a crank shaft
of the gasoline engine 2. The output rotational speed sensor 22
detects an output side rotational speed NO (i.e., rotational rate)
of the automatic transmission 6. Further, the engine output torque
control device 18 receives a detection signal from an accelerator
operation amount sensor 26 and a shift signal representing a gear
position from a transmission control apparatus controlling a
transmission state of the automatic transmission 6. The accelerator
operation amount sensor 26 detects an accelerator operation amount
ACCP corresponding to an operation amount of an accelerator pedal
24 operated by a driver. The engine output torque control device 18
executes a computation based on the above signals and various data
to calculate a target throttle opening degree Tat and controls the
driving motor 16a based on the target throttle opening degree Tat
to adjust the output of the rotational drive force of the gasoline
engine 2.
FIG. 2 illustrates a control block diagram of an engine output
torque control portion 30 for controlling the rotational drive
force, or the torque output in this case, within the engine output
torque control device 18. The engine output torque control portion
30 includes a turbine rotational speed calculation section 30a, a
vehicle speed calculation section 30b, a target engine torque
calculation section 30c, a torque converter model 30d, a target
rotational speed adjustment section 30e, and an engine model
30f.
The turbine rotational speed calculation section 30a calculates a
turbine rotational speed NT corresponding to a rotational speed of
a turbine shaft 4a of the torque converter 4, based on the gear
position and the output side rotational speed NO of the automatic
transmission 6. The vehicle speed calculation section 30b
calculates a vehicle speed SPD based on the output side rotational
speed NO and a differential gear ratio. In this case, the vehicle
speed SPD may be a value which is calculated by another vehicle
control system independently. The target engine torque calculation
section 30c calculates a target engine torque Te based on the
vehicle speed SPD and the accelerator operation amount ACCP. The
torque converter model 30d is used for calculating a target model
rotational speed NEm of the gasoline engine 2 based on the turbine
rotational speed NT and the target engine torque Te. The target
rotational speed adjustment section 30e is structured such as to
calculate a target rotational speed NEt based on the actual
rotational speed NE and the target model rotational speed NEm. The
engine model 30f is used for calculating a corresponding target
throttle opening degree TAt based on the target rotational speed
NEt and the target engine torque Te. In this embodiment, a map
MAPtat (FIG. 5) as mentioned below is obtained based on a standard
engine or an average engine is used for the engine model 30f.
The target engine torque calculation section 30c is a portion which
is arrived at based on a model generated during designing of output
performance for the gasoline engine 2. For example, the target
engine torque calculation section 30c represents a relation among
the vehicle speed SPD, the accelerator operation amount ACCP and
the target engine torque Te, as illustrated in FIG. 3.
The torque converter model 30d represents a relation among input
side and output side input torques obtained based on the standard
torque converter or the average torque converter, the input
rotational speed, the output torque and the output rotational
speed. If any two of the input torque, the input rotational speed,
the output torque and the output rotational speed are determined,
the other two values are uniquely determined as well. Accordingly,
when the target engine torque Te and the turbine rotational speed
NT are determined, the target model rotational speed NEm is
uniquely determined.
The target rotational speed adjustment section 30e performs the
process as illustrated in a control block diagram in FIG. 4.
Specifically, the target rotational speed NEt is calculated by
setting the target model rotational speed NEm as an initial value
for the target rotational speed NEt and correcting the target
rotational speed NEm based on a difference between the target model
rotational speed NEm and the actual rotational speed NE. In this
case, a control correction amount dy is calculated by executing a
PI control calculation for the difference dx between the target
model rotational speed NEm and the actual rotational speed NE at a
PI control calculation section 32. Further, the control correction
amount dy is limited at a correction amount limiting section 34 to
determine final correction amount dz. In this embodiment, the
control correction amount dy is limited to be equal or smaller than
the difference dx between the target model rotational speed NEm and
the actual rotational speed NE. Then, the target rotational speed
NEt is calculated by correcting the target model rotational speed
NEm by the final correction amount dz. The target rotational speed
adjustment process is described in detail below.
The engine model 30f includes a map MAPtat for determining the
target throttle opening degree TAt by using the target rotational
speed NEt and the target engine torque Te as parameters, as
illustrated in FIG. 5. The map MAPtat represents a relation in a
steady state among the rotational speed, the engine torque and the
throttle opening degree which are obtained from experiment with
regard to the standard engine or the average engine.
FIG. 6 illustrates a flow chart performing the process of the
control block diagram as mentioned above as a computer process. The
present process is performed, for example, as interrupt processing
per 50 ms.
When the process starts, the actual rotational speed NE, the output
side rotational speed NO, the accelerator operation amount ACCP,
the throttle opening degree TA and the transmission gear position
which have been already obtained from the respective sensors 20,
22, 26 and 16b and the transmission control apparatus are read into
a working memory within the engine output torque control device 18
(S100).
Next, the turbine rotational speed NT is calculated by Formula 1
(S102) NT.rarw.NO.times.transmission gear ratio [1]
Then, the vehicle speed SPD is calculated by Formula 2 (S104).
SPD.rarw.NO.times.differential gear ratio [2]
This calculation may not be performed and, instead, the value of
the vehicle speed SPD may be calculated by another vehicle control
system independently.
Next, the target engine torque Te is calculated based on the
accelerator operation amount ACCP and the vehicle speed SPD in
accordance with the map MAPte illustrated in FIG. 3 (S106). Then,
as described above, the target model rotational speed NEm is
calculated based on the turbine rotational speed NT and the target
engine torque Te in accordance with the torque converter model
(S108).
Next, a target rotational speed adjustment process (S110) is
performed to calculate the target rotational speed NEt. The target
rotational speed adjustment process (S110) carries out a process as
illustrated in FIG. 7 corresponding to FIG. 4. Specifically, the
difference dx between the target model rotational speed NEm and the
actual rotational speed NE is calculated by Formula 3 (S120).
dx.rarw.NEm-NE [3] The PI control calculation is performed as
expressed in Formula 4 by using the difference dx (S122).
dy.rarw.Kpdx+Ki.SIGMA.dx [4]
wherein Kp and Ki are proportion coefficients and .SIGMA.dx is an
integral of the difference dx per control cycle.
Then, the limiting process is carries out (S124). In the limiting
process, the value of the control correction amount dy determined
as mentioned above is set to the final correction amount dz while
setting the difference dx as a limit value (S124). In other words,
if the control correction amount dy is greater than zero (0) and
dy>dx is satisfied, the difference dx is set to the value of the
final correction amount dz. If the control correction amount dy is
greater smaller than zero (0) and dy<dx is satisfied, the value
of the difference dx is set to the final correction amount dz. In
the other cases, the control correction amount dy is set to the
final correction amount dz. The target model rotational speed NEm
is corrected to the target rotational speed Net by the final
correction amount dz as calculated above, as expressed in Formula 5
(S126). NEt.rarw.NEm-dz [5]
FIG. 8 is a timing chart illustrating an example of the control in
the first embodiment. In the timing chart, When the driver
depresses the accelerator pedal 24 (t=t0), the target engine torque
Te is rapidly increased (S106). The target model rotational speed
NEm is also rapidly increased accordingly (S108). The actual
rotational speed NE is increased in a delayed manner due to the
long dead time. The value of the model rotational speed NEm is
corrected in such a manner as to gradually approach the actual
rotational speed NE to set the target rotational speed NEt while
setting the difference dx between the target model rotational speed
NEm and the actual rotational speed NE (FIG. 7, t.gtoreq.t0) as the
limit for the correction. Accordingly, the target rotational speed
NEt finally approaches the actual rotational speed NE and coincides
with the actual rotational speed NE (t.gtoreq.t1).
When, the driver returns the accelerator pedal 24 (t=t2), the
target engine torque Te is rapidly decreased (S106). The target
model rotational speed NEm is also rapidly decreased accordingly
(S108). The actual rotational speed NE is decreased in a delayed
manner due to the long dead time. The value of the model rotational
speed NEm is corrected in such a manner as to gradually approach
the actual rotational speed NE while setting the difference dx as
the limit for correction and set the corrected model rotational
speed NEm as the target rotational speed NEt (FIG. 7, t.gtoreq.t2).
Accordingly, the target rotational speed NEt finally approaches the
actual rotational speed NE and coincides with the actual rotational
speed NE (t.gtoreq.t3).
In accordance with the first embodiment, the vehicle speed
calculation section 30b, the target engine torque calculation
section 30c, the torque converter model 30d and the target
rotational speed adjustment section 30e corresponds to the target
rotational speed calculation section. The vehicle speed calculation
section 30b and the target engine torque calculation section 30c
corresponds to the target drive force setting section. The engine
model 30f corresponds to the control amount calculation section.
The output side rotational speed detection section corresponds to
the turbine rotational speed calculation section 30a. The torque
converter model 30d corresponds to the target model rotational
speed calculation section. The engine rotational speed sensor 20
corresponds to the rotational drive force source rotational speed
detection section. The rotational output sensor 22 corresponds to
the transmission output shaft rotational speed detection
section.
In the engine output torque control process (FIG. 6), the steps
S100 to S110 correspond to the process of the target rotational
speed calculation section. The steps S104 and S106 correspond to
the process of the target drive force setting section. The step
S112 corresponds to the process of the control amount calculation
section. Further, the step S108 corresponds to the process of the
target model rotational speed calculation section. The step S110
(FIG. 7: the target rotational speed adjustment process)
corresponds to the process of the target rotational speed
adjustment section.
The first embodiment has the following advantage.
(1) In the target rotational speed adjustment process (FIG. 7)
performed by the target rotational speed adjustment section, the
target rotational speed NEt is calculated by correcting the value
of the target model rotational speed NEm to gradually approach the
actual rotational speed NE.
The initial value of the control amount (or the target rotational
speed NEt used for calculating the target throttle opening degree
Tat) is the target model rotational speed NEm. That is, the actual
rotational speed NE itself having the long dead time is not used
for the target rotational speed NEt from the beginning, hunting is
not generated during control of the drive force (the engine output
torque in this case) of the gasoline engine 2 even if the target
throttle opening degree TAt is calculated based on the target
rotational speed NEt.
The correction is carried out in such a manner as to gradually
approach the target rotational speed NEt to the actual rotational
speed NE in accordance with the PI control calculation.
Then the target rotational speed NEt finally converges on the
actual rotational speed NE. The relation represented with respect
to the rotational drive force source model (the engine model 30f)
and the rotational drive force source output transmission model
(the torque converter model 30d) is a standard or average relation
and a deviation may exist between the target model rotational speed
NEm and the actual rotational speed NE in a steady state. However,
the target rotational speed NEt converges with the actual
rotational speed NE to become a target rotational speed reflecting
to the actual relation. Accordingly, the target rotational speed
NEt becomes the target rotational speed which complies with each
actual gasoline engine 2 at a high precision.
In the engine output torque control device 18, or the rotational
drive force source control apparatus, hunting of the engine during
control is prevented and the deviation between the actual
rotational speed NE and the target rotational speed Net is reduced
or prevented. The gasoline engine 2 for the vehicle controlled as
mentioned above can provide for smooth vehicle travel.
In the second embodiment, the target rotational speed adjustment
section 30e as illustrated in FIG. 2 performs a process as
illustrated in a control block diagram of FIG. 9, instead of FIG.
4. FIG. 9 is the same as FIG. 4 in that the initial value of the
target rotational speed NEt is the target model rotational speed
NEm and the target model rotational speed NEm is corrected based on
the difference dx between the target model rotational speed NEm and
the actual rotational speed NE to calculate the target rotational
speed NEt. However, in FIG. 9, the final correction amount dz is
calculated by executing a first order lag process of the difference
dz by a first order lag processing section 36. Then, the target
model rotational speed NEm is corrected based on the final
correction amount dz to calculate the target rotational speed NEt.
Accordingly, a process illustrated in FIG. 10 is performed as the
target rotational speed adjustment process instead of FIG. 7. Since
the other structures are the same as those in the first embodiment,
a description will be given of the other structures with reference
to FIGS. 1 to 3, 5 and 6.
In the target rotational speed adjustment process (FIG. 10), a
correction is performed so as to approach the target rotational
speed NEt to the actual rotational speed NE gradually by using the
first order lag process. That is, as expressed in the Formula 3 as
mentioned above, the difference dx between the target model
rotational speed NEm and the actual rotational speed NE is
calculated (S220).
Then, the final correction amount dz is calculated in accordance
with the first order lag processing as expressed by Formula 6 by
using the difference dx (S222). dz.rarw.dx(1-exp(-t/T)) [6] wherein
(1-exp(-t/T)) is a first order lag system, T is a time constant,
and is an elapsed time from a rapid change time, such as a stepped
change, of the target model rotational speed NEm caused by a change
in an acceleration opening degree ACCP or the like. The time
constant T is set in such a manner that the resulting final
correction amount dz gradually changes the target rotational speed
NEt from the target model rotational speed NEm side to the actual
rotational speed NE side.
The value of the target model rotational speed NEm is corrected by
the final correction amount dz as calculated above to obtain the
target rotational speed NEt, as expressed in the Formula 5
(S224).
FIG. 11 is a timing chart showing an example of a control in the
second embodiment. When the driver depresses the accelerator pedal
24 (T=t10), the target engine torque Te is rapidly increased
(S106). Accordingly, the target model rotational speed NEm is also
rapidly increased (S108). The actual rotational speed NE is
increased in a delayed manner due to the long dead time. The value
of the target model rotational speed NEm corrected by the final
correction amount dz calculated by the first order lag process
(S222) is set to the target rotational speed NEt in such a manner
that the target model rotational speed NEm gradually approaches the
actual rotational speed NE (FIG. 10, t.gtoreq.t10). Therefore, the
target rotational speed NEt finally comes close to the actual
rotational speed NE, and coincides with the actual rotational speed
NE (t.gtoreq.t11).
When the driver returns the accelerator pedal 24 (t=t12), the
target engine torque Te is rapidly decreased (S106). The target
model rotational speed NEm is also rapidly decreased accordingly
(S108). The actual rotational speed NE is decreased in a delayed
manner due to the long dead time. The value of the target model
rotational speed NEm is corrected by the final correction amount dz
as mentioned above in such a manner as to approach to the actual
rotational speed NE and the corrected model rotational speed NEm as
the target rotational speed NEt (FIG. 10, t.gtoreq.t12). Therefore,
the target rotational speed NEt finally approaches the actual
rotational speed NE and coincides with the actual rotational speed
NE (t.gtoreq.t13).
In the second embodiment, a step S110 (FIG. 10: target rotational
speed adjustment process) corresponds to the process of the target
rotational speed adjustment section.
The second embodiment has a following advantage.
(1) Instead of the PI control calculation, the first order lag
process is performed. However, the same effect as that of the first
embodiment may be caused. That is, hunting during control is
prevented and the deviation between the actual rotational speed NE
and the target rotational speed Net is reduced or prevented.
In the third embodiment, a target rotational speed adjustment
process as illustrated in FIG. 12 is performed instead of the
process of the target rotational speed adjustment section 30e of
FIG. 7 in the first embodiment. In the target rotational speed
adjustment process (FIG. 12), when the target model rotational
speed NEm is rapidly changed, the target rotational speed NEt is
changed from the target model rotational speed NEm toward the
actual rotational speed NE in a repetitive way by increments of a
fixed rotational speed. Since the other structures are the same as
those in the first embodiment, a description will be given of the
other structures with reference to FIGS. 1 to 3, 5 and 6.
If the target rotational speed adjustment process (FIG. 12) is
performed, it is firstly determined whether or not the target model
rotational speed NEm is rapidly changed (S320). The rapid change in
the target model rotational speed NEm is determined based on a
magnitude of the change amount of the target model rotational speed
NEm per unit time. For example, an absolute value of the change
amount is larger than the reference value, the determination is
affirmative. Thus, such a rapid change in the target model
rotational speed NEm is determined that the great difference is
generated between the actual rotational speed NE and the target
model rotational speed NEm.
Next, if the target model rotational speed NEm is rapidly changed
(yes in S320), the final correction amount dz is cleared (S322).
Then the target model rotational speed NEm is set to the target
rotational speed NEt (S324).
Next, it is determined whether or not the final correction amount
dz is equal to or more than the absolute value (|NEm-NE|) of the
difference between the target model rotational speed NEm and the
actual rotational speed NE (S326). Since a relation dz<|NEm-NE|
is satisfied (no in S326) at the beginning of the rapid change in
the target model rotational speed NEm, the final correction amount
dz is increased by a gradual incremental amount dne as expressed in
Formula 7 (S328). dz.rarw.dz+dne [7]
The value of the gradual incremental amount dne is, for example,
several rpm to ten and several rpm.
Next, it is determined whether or not the target model rotational
speed NEm is greater than the actual rotational speed NE (S330). If
the relation NEm>NE is satisfied (yes in S330), the target
rotational speed NEt is set by subtracting the final correction
amount dz from the target model rotational speed NEm as expressed
in Formula 8 (S332). NEt.rarw.NEm-dz [8]
Meanwhile, if the relation NEm>NE is not satisfied (no in S330),
the target rotational speed NEt is set by adding the final
correction amount dz to the target model rotational speed NEm as
expressed in Formula 9 (S334). NEt.rarw.NEm+dz [9]
If the step S332 or the step S334 is finished, the step temporarily
exits the target rotational speed adjustment process.
If the rapid change in the target model rotational speed NEm is
finished in the next control cycle (no in S320), it is then
determined whether or not the relation dz.gtoreq.|NEm-NE| is
satisfied (S326). If the state dz<|NEm-NE| is maintained (no in
S326), the process of the Formula 7 is performed in the step S328
as mentioned above to increase the final correction amount dz by
the gradual incremental amount dne. Then the step S332 or the step
S334 is performed in accordance with whether or not the relation
NEm>NE is satisfied (S330).
Subsequently, negative determination is made in the step S320,
negative determination is made in the step S326, the gradual
increase in the final correction amount dz is performed in the step
S328, and the setting of the target rotational speed NEt in the
step S332 or the step S334 are carried out repeatedly. Accordingly,
the target rotational speed NEt is gradually changed from the
target model rotational speed NEm to the actual rotational speed
NE.
Then, if the changes in the target model rotational speed NEm and
the actual rotational speed NE are generated and the relation
dz.gtoreq.|NEm-NE| is finally satisfied (yes in S326), the value of
the actual rotational speed NE is set as the target rotational
speed NEt (S336).
Subsequently, if the rapid change in the target model rotational
speed NEm is not generated (no in S320), and the target model
rotational speed NEm and the actual rotational speed NE are stable
(yes in S326), the actual rotational speed NE is kept as the target
rotational speed Net (S336).
The same control as the timing chart of FIG. 11 performed by the
process mentioned above.
In the third embodiment, the step S110 (FIG. 12) corresponds to the
process of the target rotational speed adjustment section.
The third embodiment has a following advantage.
(1) Instead of the PI control calculation, the target rotational
speed NEt is gradually changed by increments of the fixed
rotational speed from the target model rotational speed NEm to the
actual rotational speed NE. In accordance with this structure, the
same effect as that of the first embodiment may be caused. That is,
hunting of the engine during control is prevented and the deviation
between the actual rotational speed NE and the target rotational
speed Net is reduced or prevented.
The above embodiments may be modified as follows.
In the first embodiment mentioned above, the control correction
amount dy is continuously determined in accordance with the PI
control calculation during the activation of the engine output
torque control device 18. However, alternatively, the PI control
calculation may be started from a state in which the control
correction amount dy is cleared, by initializing the target
rotational speed NEt to the target model rotational speed NEm, at a
time when the target model rotational speed NEm is rapidly
changed.
In the third embodiment, the time of the rapid change in the target
model rotational speed NEm is determined based on the stepped
change in the target model rotational speed NEm or the change
amount per unit time. However, alternatively, it is possible to set
the time at which the target model rotational speed NEm separates
from or intersects the actual rotational speed NE as illustrated by
timings t0, t2, t10 and t12 in FIGS. 8 and 11 to the rapid change
time in the target model rotational speed NEm.
Instead of the PI control calculation performed in the first
embodiment, an I control calculation may be performed. That is, the
control correction amount dy may be calculated based on
"Ki.SIGMA.dx" only in the calculation of the Formula 4 in the step
S122 during the target rotational speed regulating process (FIG.
7).
In the third embodiment, the target rotational speed NEt changes
from the target model rotational speed NEm to the actual rotational
speed NE by increments of the fixed rotational speed. However, the
target rotational speed NEt may change by increments of a fixed
rate of the difference dx.
While the source of rotational drive force is a gasoline engine in
the above embodiments, a diesel engine may be used instead. In that
case, the control amount is a fuel injection amount.
Other than the above-described internal combustion engine, an
electric motor such as a fuel cell vehicle or a hybrid engine with
an internal combustion engine and an electric motor may be
used.
The present invention is also applicable to a source of rotational
drive force in which the source includes a manual clutch or other
clutches lacking a torque converter in the output transmission
system for a rotational drive force source.
* * * * *